LiMn2O4 as a large-capacity positive material for lithium-ion batteries

Abstract

The layered oxide materials LiMO 2 (M = Co, Ni) have been investigated as the cathode materials for secondary lithium batteries. 1,2 LiMn 2O4 is one of the most promising alternatives to the high-cost cobalt-positive materials including LiCoO2 and LiNi 1/3Co1/3Mn1/3O2 because of its low cost, lower toxicity, and material safety in the charge state. LiMn 2O4 shows excellent cycle performance at the 4-V region.3,4 However, the cycle capacity is lower than other cathode materials such as LiMO2 (M = Co, Ni). If it is possible to reversibly insert the excess lithium into LiMn2O4 in the 3-V region, this disadvantage should be overcome. However, in previous studies it was reported that a full lithium insertion/extraction process has led to gradual decay of its original structure, and LiMn2O4 cathode has shown a drastically fast capacity failure when it was used in the 3- to 4-V region.5 In this chapter, we report on the relation between the crystal structure of LiMXMn2-XO4 (M = Mn, Co, Ni) and the electrochemical properties in the 3- to 4-V region. We describe the synthesis of the materials with large rechargeable capacity at wide voltage region. © 2009 Springer Science+Business Media, LLC.